1. Field of the Invention
The present invention relates to mobile communications and, more particularly, to achieving proxy mobile node (MN) capability in a Mobile Internet Protocol (IP) infrastructure.
2. Description of the Related Art
Mobile Internet Protocol (IP) is an infrastructure and methodology for providing node mobility in an Internet environment. It allows transparent routing of IP packets or datagrams to mobile nodes over the Internet, which allows mobile nodes to change their point-of-attachment to a home network or the Internet without changing their IP address. Such a flexible mobility functionality advantageously enhances network performance in telecommunications or wireless applications.
TCP/IP is a set of protocols developed by the U.S. Department of Defense for communications over interconnected, sometimes dissimilar, networks which has become the de facto standard for data transmission over networks, including the Internet. IP (Internet protocol) is the protocol within TCP/IP that governs the breakup of data messages into packets, the routing of the packets from source to destination, and the reassembly of the packets into the original data messages at the destination.
In Mobile IP, each mobile node is identified by its home address, regardless of its current point of attachment or connection to the Internet. A mobile node (MN) is a host or router that changes its points of attachment or connection from one network or subnetwork to another. This change in location occurs without changing its IP address. Thus, the mobile node may continue to communicate with other Internet nodes at any location using its (constant) IP address, assuming link-layer connectivity to a point of attachment or connection is available.
FIG. 1 is a diagram that generally illustrates a Mobile IP network known in the art. Provided in the Mobile IP network are the mobile node (MN) 10, at least two base stations (17 and 19) connected to the Internet, and a home network 27 also connected to the Internet. A radio tower serves each of the base stations, e.g., radio towers 17A and 19A for the base stations 17 and 19, respectively.
MN 10 is shown as including a personal computer (PC 100) of an end user connected with customer premise equipment (e.g., CPE 101 that connects the end user's PC to a wireless network). Customer premise equipment is typically the equipment located at the customer's site which denotes the demarcation point between the customer (or end user) and the service provider, e.g., a T1 line, wireless modem, radio, cable modem, digital subscriber line (DSL) or asymmetric digital subscriber line (ADSL) modems.
The base stations 17 and 19 include Foreign Agent (FA) 170 and 190, respectively. In Mobile IP, a foreign agent is a router on a mobile node's visited network that provides routing services to the mobile node to which it is registered. The Foreign Agent delivers packets or datagrams to the Mobile Node (e.g., MN 10) from the mobile node's home agent (HA) 25 via tunneling through the Internet. A tunnel is a technology that enables one network to send its data over another network's connections. It works by encapsulating a network protocol (such as Mobile IP) within packets carried by the second network. For packets or datagrams sent by a mobile node, the foreign agent can serve as a default router for registered mobile nodes, and provide reverse tunneling if requested.
The home network 27, which could be an ISP or some other address assigning authority, includes the Mobile IP Home Agent (HA) 25 and a server 20. In Mobile IP, a home agent is a router on a mobile node's home network that tunnels packets or datagrams to the MN when it is away from the home location, and maintains current location information for the mobile node. The server 20 is what the end user at the MN is attempting to access, although the end user may be attempting to access a server that is located elsewhere on the Internet.
MN 10 is assigned a Mobile IP address and is responsible for registering it with the Mobile IP home agent (HA 25) at the home network 27. The mobile node functionality of MN 10 ensures that, as the end user moves between base stations (e.g., from MN 10 to MN 10′), the same Mobile IP address for MN 10 is maintained. When the mobile end-user at MN 10 moves from the transmitting range of the base station 19 to that of the base station 17, the MN 10 (through CPE 101) detects the new base station 17 and re-registers with the home agent HA 25. In doing so, it informs the home agent 25 of its new point of attachment, i.e., its new foreign agent FA 170. HA 25 acknowledges the re-registration and updates its files to reflect the new location (namely MN 10′) of the end-user in the transmitting range of the base station 17. Once the new registration is complete, HA 25 forwards all Mobile IP packets destined for MN 10 to the new FA 170 instead of the previous FA 190.
FIG. 2 is a flow diagram that illustrates a method for operating the Mobile IP network known in the art as shown in FIG. 1. In step 201, a Mobile IP address is assigned to the MN 10. The base station (BS) 19 (through radio tower 19A) broadcasts a pilot signal within its transmitting range (step 203). Since the MN 10 is within the transmitting range of the BS 19, it detects the pilot signal (step 205), and sends a registration request to the FA 190 at the BS 19 (step 207). The FA 190 relays the registration request by the MN 10 to the HA 25 at the home network 27 (step 209). The MN 10 is then registered with the HA 25 (which can send back an acknowledgment), with the current FA being the FA 190 (step 211). Mobile IP packets or datagrams can then be transmitted between the home network 27 and the MN 10.
In step 213, it is determined whether the MN 10 detects a new base station (BS). Should the end user be mobile and move within the transmitting range of a new BS, e.g., to the position indicated as MN 10′, the CPE 101′ detects the movement and the control flow goes to step 215. MN 10′ then sends a registration request to the new FA 170 at the new BS 17 (step 215). The new FA 170 relays the registration request by the MN 10′ to the HA 25 at the home network 27 (step 217). MN 10′ is then re-registered with the HA 25, with the current FA now being the new FA 170 (step 219). The re-registration is acknowledged by an acknowledgment signal sent by HA 25 (step 221). The control flow is then directed to step 223.
If in step 213 the MN does not detect a new BS, i.e., the MN 10 is still within the transmitting range of the BS 19, then the control flow is sent directly to step 223. In step 223, data are encapsulated into Mobile IP packet(s) for transmission between a source and destination, e.g., the MN 10 and the home network 27. If the data are transmitted from the home network 27 to the MN 10, the HA 25 encapsulates the data into Mobile IP packet(s) for transmission (step 223) and forwards them to the current agent, (step 225). If the data are transmitted from the MN 10 to the home network 27, then the foreign agent (FA 190 or FA 170 depending on location) encapsulates the data into Mobile IP packet(s) for transmission and forwards them to the HA 25 (step 225).
The Mobile IP packet(s) are unencapsulated by the agent at the destination into the data as originally transmitted (step 227). If the data are transmitted from the home network 27 to the MN 10, the foreign agent unencapsulates the Mobile IP packets into original data (step 227) and forwards them to the MN 10 (step 229). If the data are transmitted from the MN 10 to the home network 27, then the HA 25 unencapsulates the Mobile IP packets into original data (step 227) and forwards them to the home network 27 (step 229).
The MN functionality described above requires the installation of software in either the PC 100 or the CPE 101 at the MN 10. This requirement leads to the necessity of installing software for the MN (in the PC or the CPE) for every end user of the Mobile IP network. Such a requirement complicates the configuration of PC 100 and CPE 101, and disadvantageously adds burden to deployment of a Mobile IP network. In addition, it adds overhead to the wireless interface by requiring the sending of registration messages on a periodic basis.
Therefore, there is a general need in the art for an improved method and system for communicating information between a source and a destination using Mobile IP. Particularly needed in the art is a Mobile IP methodology and system that simplifies the configuration of the MN and the network infrastructure. Also needed is a Mobile IP network that provides MN functionality without unduly burdening the configuration of the MN.